The present invention relates to the technical field of household electrical cooking appliances of the toaster type and concerns more particularly a means for permitting the walls of the housing of the toaster to be made rigid.
Most present day toasters have one or several chambers for heating bread, housed, with mechanisms for displacing the bread support carriage and the control electronics, at the interior of a plastic housing. The heating chambers often have a roof made of metal or of a material having a certain thermal inertia.
In order to reduce the costs of the plastics utilized for the housing, this latter is often spaced from the heating elements that are brought to a high temperature, such as the roof of the toaster. However, the natural elasticity of the plastic induces, when the toaster is gripped by the lateral walls, a certain risk of contact between said walls of the housing and the roof, or even the heating chamber, which can lead to, if the toaster is in operation, or has just halted operation, a risk of local melting of the housing.
In order to overcome this problem, numerous manufactures propose an upper edge of the housing of the toaster, which permits the walls to be sufficiently rigidified to avoid all contact with the roof. This edge is generally situated above the roof. Insulating crosspieces connecting the hot surfaces of the roof to the walls can complete the stiffening of the walls of the housing.
One of the consequences of the presence of this edge is the surface of the roof limited by said edges and thus a significant lateral obstruction of the toaster with respect to the useful surface of the roof.
Moreover, the presence of this upper edge requires that the fabrication of the housing necessarily be in two steps, the edge not permitting molding of the bottom of the housing with the vertical walls.
One of the objects of the present invention is to overcome the problems of the prior art by providing a toaster whose housing is rigidified in order to avoid all contact with the roof, without significantly increasing the thermal transfer from the roof toward the housing.
Another goal of the present invention is to reduce the quantity material necessary for fabrication of the housing.
Another object of the present invention is to permit the fabrication of a toaster housing having four lateral walls and a base plate in a single molding step.
The present invention is achieved with the aid of a means for stiffening a toaster housing, said housing being open at its upper part and being defined by one or several vertical walls resting on a base plate, characterized in that it consists of a ring or ring portion capable of being mechanically linked with the upper parts of the walls of the housing.
Advantageously, the form of the ring or portion of a ring, as seen in a plan view, corresponds substantially to the form or a part of the form of the peripheral edge of a housing on which it is arranged. Notably, according to the toaster model, this ring can have a rectangular form, or an oval form, or any other compound form.
This ring or ring portion which is peripheral along the circumference of the housing, situated at the top of said housing, permits deformation of the walls of the housing to be limited when these walls are urged in flexure, particularly when the user grasps the toaster by said walls. By limiting their deformation, the risk of contact between these walls and the parts of the heating chamber which can present an elevated temperature, is reduced. Thus, the walls of the housing of the toaster can be made thinner, reducing the quantity of material and thus the costs.
In a particularly advantageous manner, the stiffening ring or ring portion is made of a material having low thermal conductivity. This property permits said ring or ring portion to be given, in addition to its function of rigidifying the walls of the housing, a function of thermal insulation of the walls of the housing relative to the parts of the toaster that experience an increased temperature, such as the roof of the toaster.
According to a particular form of construction of the invention, the ring or ring portion is made of a heat resistant plastic, permitting attainment of the two desired properties of stiffening and thermal insulation, while offering a material that has a low cost and is easy to use. According to one of the embodiments of the invention, the stiffening ring or ring portion has a transverse cross section at least partially U-shaped such that the upper edge of the housing can fit into said ring or ring portion. This partial overlapping of the two elements permits, when a compression force is exerted on the toaster walls, the force to be transferred to the ring or ring portion.
As a complement or a variant of the preceding embodiment, the ring or ring portion has means for attachment to the walls of the housing of the toaster, permitting a mechanical connection to be assured with the walls of the housing.
The present invention equally relates to a toaster having a frame arranged in a housing, at least one vertical toasting chamber open at the upper part of the housing, a peripheral roof at the opening of the toasting chamber, located essentially in the spaced defined by the housing and having an upper edge provided with openings, heating means situated in proximity to the toasting chamber, characterized in that the toaster has a means for stiffening the walls of the housing as described previously.
Such a roof can be designed in a form and of a material permitting reheating to be effectuated on food products placed directly on said roof.
According to one of the embodiments, the stiffening ring or ring portion has a support zone for the roof of the toaster. By permitting connection of the roof to the walls of the toaster by the intermediary of the rigidifying means, the annular space generally present between the roof and the housing is eliminated, which permits, in addition to rigidifying the walls of the toaster, to exploit the reheating function of the roof, while reducing the risks of introduction of crumbs or objects into the interior or the toaster.
According to another embodiment, the ring or ring portion has one or several ribs, having a function of centering the roof. The rib or ribs are such that they leave only a functional play with the roof, in a manner such that the centering of the roof is automatically effectuated by the ring or ring portion when these two elements are disposed on the toaster.
Moreover this centering of the roof by the ribs permits a defined spacing of the walls of the housing of the toaster from said roof to be assured, the layer of air thus defined reinforcing the thermal insulation of the ring when this latter is made of a thermal insulating material. The value of the air layer can be adjusted by the form given to the ring.
According to a variant of this embodiment, certain of these ribs achieve a centering of the roof at the exterior thereof, while others achieve a centering at the interior of the roof. The ribs are then situated, either in a facing relation on a substantially horizontal internal edge of the ring or ring portion, in such a manner as to provide a space for receiving the roof between them, or offset in alternation for an internal guiding/external guiding of the roof.
As a complement of these variants of construction, the toasting chamber is delimited by two substantially vertical gripping grids capable of moving toward one another when the heating elements are supplied with power, said gripping grids having an upper edge that is substantially perpendicular to said grids and oriented toward the exterior of the chamber, in a manner to partially close the heating chamber, when they have moved towards one another, to thus divert the ascending hot air flow generated by the heating elements.
This configuration permits the heat flow generated by the heat elements to be distributed as desired so that it will not be concentrated solely toward the central part of the chamber, the edge thus arranged acting as a deflector in order to deflect the hot air flow. The ascending heat flow, partially deflected, is thus distributed, which aids a uniform reheating of bread placed on the sheet.
Advantageously, reflectors are associated with the heating elements, said reflectors having, toward their upper end, a narrowing by the intermediary of two converging slopes.
This narrowing is favorable for a good conservation of heat in the toaster in the toasting mode, while permitting an orientation of the heat flux laterally, for a uniform reheating of bread placed on the edge of the roof.
The present invention equally relates to a toaster having a frame arranged in a housing that is open at its upper part in being defined by one or several vertical walls resting on a base plate, at least one vertical toasting chamber open at the upper part of the housing, a roof peripheral to the opening of the toasting chamber, heating means situated in proximity to the toasting chamber, said housing being made of a plastic material, characterized in that the walls of the housing do not have an edge at the upper part and are molded with the base plate of the housing.
The possibility of molding the housing with the base plate generates a saving of time and permits a reduction of cost.
As a complement to the preceding form of construction, the toaster has a means for stiffening the walls of the housing as previously described.
The mechanical reinforcement of the walls of the housing such as proposed permits elimination of the upper edge as conventionally encountered and which requires a molding of the housing without the base plate. Since the edges are no longer necessary to rigidify the housing, due to the means presented, it is then possible to mold the housing with its base plate in a single piece, without adversely affecting the final rigidity of the product.